Sandy has killed at least 39 people across eight states, has left more than 8 million without power, and has absolutely crippled the mass transit system that the nation's biggest city relies upon to function, with many subway tunnels flooded.

"The New York City subway system is 108 years old, but it has never faced a disaster as devastating as last night," said Joe Lhota, chairman of the Metropolitan Transit Authority, this morning.

This super storm will certainly go down as one of the greatest ever to hit the United States, with damage amounts well in excess of Irene's $10 billion hit in 2011. EQUECAT has estimated that the damage will be on the order of $20 billion, which would put it in the neighborhood of Hurricane Ike, which struck Texas in 2008. Insured losses will likely be more than $7 billion.

Depending on the cost of repairing New York's subways, it's possible that Sandy could edge out 1992's Hurricane Andrew at around $30 billion. The hit from Hurricane Katrina in 2005 is estimated at $100 billion. (See list of the 10 worst U.S. storms, here.)

“I think the losses are going to be almost incalculable,” said New Jersey Gov. Chris Christie. “We are in the midst of search and rescue missions.” Thousands of New Jersey homes have been damaged; hundreds of feet of the Atlantic City boardwalk was destroyed, and fires raged overnight in Ocean County. In Moonachie, New Jersey, 10 miles northwest of Manhattan, a storm-weakened levy on the Hackensack River broke this morning, pouring five feet of water into the town of 2,700, forcing many to climb to their roofs. One man rescued from near the Teterboro airport told a reporter, "It was like an ocean all around," he said. "That place always gets flooded, but this time was the worst because the level of the water reached the floor of my trailer."

But the most dramatic damage reports are coming out of New York City. Last night, at the height of the storm, backup power failed at NYU Langone Medical Center, prompting an emergency evacuation of patients in the middle of the night. According to this excellent on-the-scene report from CBS's Dana Bass, four premature infants with breathing tubes were swaddled in blankets and carried out of the hospital by nurses who ventilated them by hand.

In Queens, as many as 100 homes were destroyed in a great, wind-fanned fire despite the efforts of 190 firefighters. By one account, some rescued residents of the neighborhood had been trapped in their homes between thigh-deep floodwaters and flaming roofs.

A giant electrical transformer station on East 14th Street exploded last night in a blue-white fireball -- knocking out power to most of lower Manhattan (including Forbes headquarters).

The worst damage in the Big Apple has come from the 13-foot storm surge that swamped the Battery and dozens of blocks from the South Street Seaport through the Lower East Side and into Alphabet City. The foundations of the new World Trade Center were flooded. The surge washed over Fire Island, off the south shore of Long Island, destroying homes and docks and leaving 60 people trapped.

In the realization of a nightmare scenario, the surge waters poured into subway tunnels. The Brooklyn-Battery tunnel was inundated as were seven tunnels under the East River and the Holland Tunnel connecting Manhattan to New Jersey. Pictures taken Monday night showed subway stations flooded above platforms throughout Manhattan.

The Metropolitan Transist Authority said there was no time table for getting the subways back in action. Late Monday the head of the MTA said subway service would be down for at least a week.

Just getting the water out of the system will take days of pumping, then workers will have to inspect every inch of the system for damage. The subway system is accustomed to pumping out groundwater and rainwater -- dealing with 13 million gallons even on dry days. But these floodwaters are saltwater, from the ocean, which is far more corrosive to electronic gear and to metal, and could be especially damaging to decades-old subway equipment.

The damage is felt far beyond. In North Carolina, a replica of the tall ship HMS Bounty sunk yesterday after being battered by Sandy's winds and waves. Captain Robin Walbridge went down with the ship and is presumed dead. The Coast Guard rescued 14 other crewmembers from the ship, which has featured in the Pirates of the Caribbean movies. One other crewmember, Claudene Christian, was pulled from the sea, but died. (Some amazing pics of the sinking here.)

In Howard County, Maryland, the power outage at a water treatment plant has caused a massive sewage leak, with 2 million gallons of human waste pouring toward the Little Patuxent River every hour. (Power was returned to the plant at midday Tuesday.)

Speaking of gross, one concern on the minds of New Yorkers is what happens to all rats when the subway floods? Rats are good swimmers, at least in calm waters, so many of the millions of vermin are likely to have escaped the waters and scurried to the safety of buildings. One possible upside: it might be the case that the biggest, meanest, dominant rats live deeper down in the subways tunnels, and so may have drowned in the flooding. At least that's according to tweets from Bora Zivkovic (@boraz), who writes for Scientific American. "Many will drown. Bloated carcasses will float to the top. They can swim, but not dive through pipes, upwards, in rough water," he wrote, citing a book called "Rats."

Among the damage reports came some hoaxes. As the storm slammed New York, CNN reported that the main trading floor of the New York Stock Exchange was under three feet of water -- quickly proven untrue. There were also false reports of a fire at a hospital in Coney Island.

One story blown way out of proportion concerned an alert issued at Exelon's Oyster Creek nuclear power plant. As surge waters rose 6.5 feet above normal, the plant sent out an alert that its water pumps might not be able to handle the deluge. No worry, though; Oyster Creek has been offline for maintenance, and the alert was made based on weather conditions, not because of any dangerous condition. Other nuclear plants were either taken offline during the storm, or taken down to reduced generation rates -- with so many power outages there was no way to put their juice into the grid.

Keeping order in the days to come will be a challenge for authorities from Virginia to Michigan. Yesterday some knuckle-heads on Twitter were advertising their intentions to do some looting in Sandy's wake. @Call_Me_WORM tweeted: "Bout to do some looting when this hurricane finally hits ... gonna get a new laptop and TV ... this hurricane might be the best thing to happen."

That's the can-do spirit!

No matter what the total damage bill comes to, it's far from insurmountable. Together, New York, New Jersey, Pennsylvania, Maryland and Connecticut have an annual GDP of $2.7 trillion, representing about 20% of U.S. GDP. Even $30 billion in damages comes to "just" 1% of that. And if rebuilding is done right, New York City will end up like New Orleans -- with stronger fortifications ready to withstand the next Big One.